The following services, among others, can be configured to launch EC2 instances:

AWS CloudFormation: You can configure a CloudFormation template to launch one or more instances on your behalf as part of a stack. For more information, see What is AWS CloudFormation? To terminate the stack and all its resources, see Terminating a Stack.

AWS Elastic Beanstalk: Elastic Beanstalk environments include EC2 instances by default, and can launch multiple EC2 instances, depending on how their Auto Scaling rules are configured. For more information, see What Is Elastic Beanstalk? To terminate an environment and all its resources, see Terminate an Environment.

AWS OpsWorks: AWS OpsWorks allows you to launch groups of AWS resources, known as stacks, according to a pre-configured template known as a cookbook. If you launch an OpsWorks stack, the cookbook might be configured to launch EC2 instances as part of the stack. To terminate the resources associated with a stack, shut down the stack.

To delete EC2 resources launched by another service, you might need to complete additional steps before or after terminating the EC2 resources, depending on which service you were using.

Check to see if someone else launched the instances

Another authorized user, such as someone else in your company, might have launched the instances as part of a project they were working on. Check with others in your company or on your team and ask if they launched the instances, or if these instances can be safely shut down.